Inductive cavitator

ABSTRACT

A tank for containing a liquid whose bottom portion is partially comprised of a housing for an inductive oscillator having a pair of rotors. The rotors move in opposite directions so as to provide an inphase reaction normal to the base of the tank to establish cavitation in liquid disposed in the tank.

United States Patent [191 [111 3,740,028 Bodine June 19, 1973 [5 1INDUCTIVE CAVITATOR [56] References Cited [76] Inventor: Albert G.Bodine, 7877 Woodley UNITED STATES PATENTS Avenue, Van Nuys, Calif-91406 3,544,073 12/1970 Bodine 259/72 x [22 Filed: Dec. 9, 1971 PrimaryExaminer-John Petrakes 21 Appl. No.: 206,567

Related US. Application Data Division of Ser. No. 856,953, Sept. 11,1969, Pat. No. 3,633,877.

l1 at- Assistant Examiner-Alan l. Cantor Attorney-Sokolski & Wohlgemuth[57] ABSTRACT 3 Claims, 3 Drawing Figures 3a 4/ 3 I g i iii INDUCTIVECAVITATOR This is a division of application Ser. No. 856,953, filedSept. 11, 1969, now US. Pat. No. 3,633,877.

There has been disclosed in prior applications to the same inventorvarious inductive oscillators working in a liquid media to clean partsor the like in the liquid. In the prior disclosures, an elastic membersuch as a rubber tubular element is disposed between an oscillator and aradiating piston which delivers the energy to the liquid. By the use ofsuch an elastic member, particularly when the system is operating atelastic resonance, it is possible to accomplish a maximization ofdelivery of power to the liquid. However, these prior systems utilizingsuch elastic members have some dis advantages.

One disadvantage of the prior systems is that the elastic member allowsthe piston surface to rock or tilt periodically in its vibratorymovement. The piston not only moves back and forth as it appliescompressional waves to the liquid, but also develops a rocking ortipping movement which is superimposed over the main vibratory movement.This rocking or tipping vibration of the piston results in portions ofit moving in what is, in effect, an amplified motion. In other words,the main vibratory motion of the piston has added to it the tippingmotion at various localized regions where the tipping movement is inphase with the main vibratory movement. Alternatively, at the oppositeedge of the piston the tipping is necessarily subtractive and this, ineffect,

reduces the amount of movement of the piston at the opposite edge.

The aforegoing secondary superimposed tipping or rocking of the pistonis due to the elastic freedom provided by an elastic member as shown inthe various prior disclosures. As a result, the main motion of thepiston resulting from the elastic member thus has superimposed upon itthe tipping motion which results from the secondary elastic vibrationsin the elastic member.

A further disadvantage of the aforementioned tipping effect is that oneportion-of the piston face moves with augmented motion relative to thebasic vibration while the opposite region of the piston face, that isthe region across the center line, moves with reduced motion. This isbecause the tipping motion subtracts from the main vibration of eachcycle. The result is that the effects in the liquid opposite the pistonare no longer uniform.

It should be pointed out that in systems where cavitation is employed inthe liquid that the cavitation is a border line condition. Therefore, ifthere is a region where the pressure excursions are slightly greaterthan they are in an adjacent region, the region having greaterexcursions will be where the predominate action of cavitation takesplace. This is a disadvantage in certain processes such as cleaning ofmetallic parts where certain regions in the parts-holding basket aresubjected to greater action than other regions in the basket. Thisproduces a non-uniform cleaning of a batch of parts.

Thus, an object of this invention is to provide a uniform energy densityof sonic application throughout a liquid body.

Another object of this invention is to provide an inductive cavitationsystem which does not have any secondary rocking or tipping of a pistonto cause nonuniform energy density.

Still another object of the invention is to provide a inductivecavitator system wherein secondary effects in the liquid body can beneutralized.

Still one further object of this invention is to provide an inductivecavitator system which permits precise control of the energy output tothe liquid.

The above and other objects of this invention are accomplished by theherein device which comprises a suitable tank for containing liquid toclean parts and the like. The bottom of the tank has an opening therein.Disposed in the opening and filling and sealing it is an oscillatorhousing for a pair of rotors. Preferably the housing is acousticallyisolated by rubber mounts or the like from the remaining bottom portionof the tank. The rotors are comprised of eccentric weights which move inan orbit so as to produce an oscillatory movement of the housing. Thusexerting vibratory energy di rectly into the liquid in the tank. The tworotors move in opposite directions so as to cancel lateral vibratoryeffects while reinforcing the vibratory energy normal to the bottom ofthe tank, thus maximizing energy input. In one embodiment of theinvention a pair of gears are meshed so as to turn in oppositedirections. These gears are driven by a single shaft connected to one ofthe gears. Each gear has connected thereto an eccentric weight forming aportion of the mass of the gear. In another embodiment of the inventionthe oscillators are of a roller type where two separate crank shafts areindividually driven through a gear box. Weights in the form of largerollers surround the eccentric crank shaft of each rotor such that whenthe shaft rotates the rollers in effect achieve an orbital motion. Onceagain, the pair of oscillators in this embodiment rotate in oppositedirections to achieve the aforegoing desired results.

It is believed that the invention will be better understood from thefollowing detailed description and drawings in which,

FIG. 1 is a partially section pictorial view of the apparatus of thisinvention,

FIG. 2 is a partially section view of one embodiment of a roller typeoscillator,

FIG. 3 is a partially section view of a second embodiment of a pair ofgeared oscillators.

It is helpful to the comprehension of this invention to make an analogybetween a mechanical resonant circuit and an electrical resonantcircuit. This type of analogy is well known to those skilled in the artand is described, for example, in Chapter 2 of Sonics by I-Iueter andBolt, published in 1955 by John Wiley and Sons. In making such ananalogy, force F is equated with electrical voltage E, velocity ofvibration u is equated with electrical current 1', mass M is equatedwith electrical inductance L, mechanical resistance (friction) R isequated with electrical resistance R, and mechanical impedance Z isequated with electrical impedance 2,. Thus, it can be shown that if amember is elastically vibrated by a sinusoidal force, F, sinmt,

0. being equal to 211 times the frequency of vibration,

that

2,, R,,, j(wM) F sinwt/u It is to be noted by reference to equation (1)that velocity of vibration u is highest where impedance 2,, is lowest,and vice versa. Therefore, a high-impedance load will tend to vibrate atrelatively low velocity, and

vice versa. Thus, at an interface between high-and lowimpedanceelements, a high relative movement results by virtue of such impedancemismatch which, as in the equivalent electrical circuit, results in ahigh reflected wave.

Of particular significance in the implementation of the methods anddevices of this invention is the high acceleration of the components ofthe system that can be achieved at sonic frequencies. It can be shownthat the acceleration of a vibrating mass is a function of the square ofthe frequency of the drive signal times the amplitude of vibration.Under resonant conditions, the amplitude of vibration is at maximum andthus even at moderately high sonic frequencies very high accelerationsare achieved.

In considering equation (1), two factors are to be noted. First, thisequation represents the total effective resistance and mass in avibrating circuit, and these parameters are generally distributedthroughout the system rather than being lumped in any one component orportion thereof. Secondly, the vibrating system often includessurrounding components, a container holding the water and the wateritself.

Turning now to FIG. 1 there is seen a tank 11 having a cylindrical wall13 of metal or suitable material and a top 15 that can be rigidlyaffixed by bolts 17. The bottom of the tank is open and has an outwardradio flange 19. Bolts 21 connect the flange to a support structure 23for the tank. Connected between the flange l9 and support 23 and alsosecured by the bolts is a rubber diaphragm 25. The diaphragm 25 servesto support an oscillator housing 27 for an oscillator 29. The housing 27isfurther secured to the rubber diaphragm 25 by a retainer ring 31. Themounting ring 33 isolates the rubber diaphragm 25 from the supportstructure 23. Thus, as can be seen the tank which contains a liquid 35has the oscillator housing 27'forming a portion of its bottom end. Thehousing 27 is free to vibrate since it is merely suspended by a rubberdiaphragm 25. To allow for freedom of movement a motor 37 drives theoscillator 29 through a drive shaft 39. The drive shaft is provided witha pair of flexible couplings 41 such as standard universal joints. Thisallows the oscillator 29 and housing 27 to move freely in the vibratorymode relative to the fixed gear box 37. A drive shaft 38 from a motor(not shown) drives the gears on box 37 and serves to rotate the driveshaft 39.

In various past systems disclosed in pending applications and issuedpatents to the same inventor a resonant system was employed utilizing amechanical oscillator which causes an elastic circuit to resonate. Thisin turn delivers this resonant elastic force to an acoustic pistonsurface which as indicated was coupled to a liquid body. However, it hasbeen found that in some situations it is very desirable to closelycontrol the amplitude of the pressure swing in the liquid. This isdifficult to accomplish when employing a resonant system since aresonant system will tend to be somewhat indeterminant as regarding thepressure swing. This is because the resonance system changes itsacoustic impedance output with changes in impedance in the liquid. Inother words, in the resonant system the oscillators utilized wouldautomatically adjust to changes in impedance and thus always maintaineda resonant output.

The herein system utilizes a mechanical inductive type oscillator whichis one that employs the reaction force from continuing the cyclic pathofa moving mass.

It is found that the resalting process of the invention is veryeconomical since large forces can be developed with reasonable cost ofoscillator design. Further, the rotary orbital oscillators used in thisinvention result in a minimum weight for the oscillator housing so thatmaximized forces in motion can be delivered to the liquid body. Althoughvarious mechanical oscillators are possible for use in the instantinvention most of them have an inherent limitation in that theoscillator will tend to be quite heavy. This wastes much of the forcewhich would otherwise be delivered to the acoustic piston or in thiscase the housing for the oscillator. As a result, the herein oscillatorsto be described provide a very lightweight structure with a high forceoutput.

Thus, the novel system of this invention is a nonresonant one. Becauseof this, the rotary motion of the oscillator must be polarized. In aresonant system the resonance itself will tend to polarize motion andthus permits a single rotor type oscillator to be utilized. In theabsence however of resonance, it is necessary to otherwise polarize themotion so that the force is not delivered equally in all directions.With an acoustic piston it is of course necessary that the force beprimarily in one direction. This is accomplished in the herein inventionby using an inductive oscillator having a pair of oppositely orbitingmasses which neutralize each other in the lateral direction but areadditive in the direction of piston vibration, usually at right anglesthereto.

Turning now to FIG. 2 there is seen in detail one of the rotary elementsof an oscillator of this invention. Inthe device of FIG. 2 two suchrotary elements are used. One only shown in detail. Each element isseparately drivenby a drive shaft 45 connected to a gear box 46. Asingle motor and drive shaft (not shown) is connected to the gear boxand serves to drive the rotors. An enclosed outer housing 47 surroundsboth of the rotor elements utilized. The housing 47 with its pistonsurface in turn is connected to the base portion of the tank, through acompliant joint, in which the device is to be used so as to radiate intothe liquid. Each of the rotary elements of the rotors comprise acylindrical housing 49 having end plates 51 and 53. An eccentric crankshaft 55 is disposed within the housing 49 having an axle portion 57extendingoutwardly from the housing through a cover plate 59 to aflexible coupling 61.

The crank shaft 55 is formed of two pieces, the first piece being themain crank portion 63 having an end 65 communicating with the axle endportion 57. The second piece of the crank 55 is end piece 65 which isaffixed to the end of the crank opposite the axle and 57 by means of asplit ring 69 and bolt 71.

An aperture 73 is provided in end plate 53 which communicates with apassage 75 formed in end piece 67. Passage 75 communicates with anopening 77 formed longitudinally through the crank 55. A plurality ofadditional secondary passages 79 in turn lead from the main opening 77through the crank to its outer surface. The purpose of the aforegoingopenings through the crank is to allow a continual flow of lubricantduring the operation of the device. The lubricant will exit theoscillator housing through apertures 81 provided in end plates 51 and53.

Surrounding the crank 55 are three separate bearings 83. In turn drivenby the bearings are three weighted rollers 85. As shown in the drawing,the rollers rotate on their outer diameter upon sleeve 87 formed of ballbearing steel or the like. In other words, as the crank 55 rotates, therollers 85 are in continuous driving contact with the inner bearings 83and carried by the outer sleeve 87 which, of course, additionally servesas a sup port bearing for the rollers.

In each end of the crank within the end plates 51 and 53 there isprovided, bearings 89 which surround the crank shaft. The bearings 89are supported from the crank shaft by a ring 91 which is separated fromthe crank shaft by a spring 93. The spring 93 is seated within-anindentation provided in the crank shaft. It is to be noted that thecrank shaft is not in tight contact with the bearings 89. Some freedomof movement is thus permitted so that there will be assurance during theoperation of the device that the rollers 85 are maintained in contactwith the outer bearing or sleeve 87. This contact will normally occurdue to the centrifugal force developed during the operation of thedevice. However, when the device is initially started, it is importantin order to prevent undesired oscillations from occuring, that therollers are initially maintained in contact with the outer sleeve 87.This is assured by the action of the springs 93. Once the centrifugalforce is sufficiently established the force of the springs are overcomeand the desired contact is maintained regardless of the spring pressure.

A further advantage of the invention particularly in the use of thepaired rotors is that one can control the energy density in the liquidby the relative phase maintained through the gear box 46. For example,if it is found that a certain region in the liquid tends to have a lowenergy density one can merely shift the gear setting in the gear box oneor two tooth differences in the standard gear phasing so as to make oneof the rotors lead or lag the other rotor. This leading or lagging ofthe rotors will tend to neutralize any secondary effects in the liquidbody which cause non-uniform energy density. Thus it can be appreciatedthe the inductive oscillator of this invention utilizing paired rotorscan be positively adjusted to obtain a particular phased effect of theenergy angle produced by the housing 47 relative to the body of liquid.This, of course, results in a very close control of the energy densityin the liquid. Such a control is virtually impossible with any otherform of oscillator which does not use paired rotors as disclosed in thisinvention.

Turningnow to FIG. 3 there is seen a second embodiment of an oscillatorof the invention. The oscillator disclosed in FIG. 3 comprises a housing95. A single drive shaft 97 enters the housing and is connected to afirst eccentric weight 99. Eccentric weight 99 has radially formed aboutits mid portion a gear 101. Bearings N13 serve to support the eccentricweight and gear within the cavity of the housing 95.

The gear 101 is intermeshed with the gear 105 of a second like rotor107. Here again the phasing of the gears can be adjusted, to get adesired phasing of the piston vibration, as mentioned in connection withFIG. 2. As shown, the eccentric weight portions of the rotors swingaround to neutralize each other in the horizontal component as shownparticularly in FIG. 3, while reinforcing each other when they swing toeither the top or the bottom of the housing 95 to reinforce the verticalcomponent. The shaft 97 is driven through a gear box 109. An axle 111from a motor, not shown, in turn drives the gears in gear box 109 andserves as a main driving force for the oscillator.

I claim:

.1. In a device for imparting sonic energy to a liquid for providingwork functions in the liquid,

a tank for containing said liquid having an opening therein, anelastomeric diaphragm attached to the edges of said opening,

an oscillator including housing means for a pair of masses mounted fororbital motion therein, acoustic piston means compliantly suspended insaid diaphragm with said acoustic piston means and diaphragm eachpartially covering said opening, the opening being completely sealedthereby, said oscillator housing means being connected to said acousticpiston means so as to deliver vibratory energy thereto, and

means for driving said masses in opposite directions to cause saidacoustic piston means to vibrate primarily along a single axis,

whereby said acoustic piston means delivers vibratory energy directly tothe liquid.

2. The combination of claim 1 wherein each orbiting mass comprises:

an eccentric crank,

and at least one roller surrounding a portion of said crank.

3. The combination of claim 2 further comprising:

separate means for driving each crank of each orbiting mass.

1. In a device for imparting sonic energy to a liquid for providing workfunctions in the liquid, a tank for containing said liquid having anopening therein, an elastomeric diaphragm attached to the edges of saidopening, an oscillator including housing means for a pair of massesmounted for orbital motion therein, acoustic piston means compliantlysuspended in said diaphragm with said acoustic piston means anddiaphragm each partially covering said opening, the opening beingcompletely sealed thereby, said oscillator housing means being connectedto said acoustic piston means so as to deliver vibratory energy thereto,and means for driving said masses in opposite directions to cause saidacoustic piston means to vibrate primarily along a single axis, wherebysaid acoustic piston means delivers vibratory energy directly to theliquid.
 2. The combination of claim 1 wherein each orbiting masscomprises: an eccentric crank, and at least one roller surrounding aportion of said crank.
 3. The combination of claim 2 further comprising:separate means for driving each crank of each orbiting mass.